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-rw-r--r--drivers/md/dm-kcopyd.c121
-rw-r--r--drivers/md/dm-raid1.c5
-rw-r--r--drivers/md/dm-snap.c5
-rw-r--r--drivers/md/dm-thin.c5
4 files changed, 132 insertions, 4 deletions
diff --git a/drivers/md/dm-kcopyd.c b/drivers/md/dm-kcopyd.c
index 68c0267..d581fe5 100644
--- a/drivers/md/dm-kcopyd.c
+++ b/drivers/md/dm-kcopyd.c
@@ -22,6 +22,7 @@
#include <linux/vmalloc.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>
+#include <linux/delay.h>
#include <linux/device-mapper.h>
#include <linux/dm-kcopyd.h>
@@ -51,6 +52,8 @@ struct dm_kcopyd_client {
struct workqueue_struct *kcopyd_wq;
struct work_struct kcopyd_work;
+ struct dm_kcopyd_throttle *throttle;
+
/*
* We maintain three lists of jobs:
*
@@ -68,6 +71,117 @@ struct dm_kcopyd_client {
static struct page_list zero_page_list;
+static DEFINE_SPINLOCK(throttle_spinlock);
+
+/*
+ * IO/IDLE accounting slowly decays after (1 << ACCOUNT_INTERVAL_SHIFT) period.
+ * When total_period >= (1 << ACCOUNT_INTERVAL_SHIFT) the counters are divided
+ * by 2.
+ */
+#define ACCOUNT_INTERVAL_SHIFT SHIFT_HZ
+
+/*
+ * Sleep this number of milliseconds.
+ *
+ * The value was decided experimentally.
+ * Smaller values seem to cause an increased copy rate above the limit.
+ * The reason for this is unknown but possibly due to jiffies rounding errors
+ * or read/write cache inside the disk.
+ */
+#define SLEEP_MSEC 100
+
+/*
+ * Maximum number of sleep events. There is a theoretical livelock if more
+ * kcopyd clients do work simultaneously which this limit avoids.
+ */
+#define MAX_SLEEPS 10
+
+static void io_job_start(struct dm_kcopyd_throttle *t)
+{
+ unsigned throttle, now, difference;
+ int slept = 0, skew;
+
+ if (unlikely(!t))
+ return;
+
+try_again:
+ spin_lock_irq(&throttle_spinlock);
+
+ throttle = ACCESS_ONCE(t->throttle);
+
+ if (likely(throttle >= 100))
+ goto skip_limit;
+
+ now = jiffies;
+ difference = now - t->last_jiffies;
+ t->last_jiffies = now;
+ if (t->num_io_jobs)
+ t->io_period += difference;
+ t->total_period += difference;
+
+ /*
+ * Maintain sane values if we got a temporary overflow.
+ */
+ if (unlikely(t->io_period > t->total_period))
+ t->io_period = t->total_period;
+
+ if (unlikely(t->total_period >= (1 << ACCOUNT_INTERVAL_SHIFT))) {
+ int shift = fls(t->total_period >> ACCOUNT_INTERVAL_SHIFT);
+ t->total_period >>= shift;
+ t->io_period >>= shift;
+ }
+
+ skew = t->io_period - throttle * t->total_period / 100;
+
+ if (unlikely(skew > 0) && slept < MAX_SLEEPS) {
+ slept++;
+ spin_unlock_irq(&throttle_spinlock);
+ msleep(SLEEP_MSEC);
+ goto try_again;
+ }
+
+skip_limit:
+ t->num_io_jobs++;
+
+ spin_unlock_irq(&throttle_spinlock);
+}
+
+static void io_job_finish(struct dm_kcopyd_throttle *t)
+{
+ unsigned long flags;
+
+ if (unlikely(!t))
+ return;
+
+ spin_lock_irqsave(&throttle_spinlock, flags);
+
+ t->num_io_jobs--;
+
+ if (likely(ACCESS_ONCE(t->throttle) >= 100))
+ goto skip_limit;
+
+ if (!t->num_io_jobs) {
+ unsigned now, difference;
+
+ now = jiffies;
+ difference = now - t->last_jiffies;
+ t->last_jiffies = now;
+
+ t->io_period += difference;
+ t->total_period += difference;
+
+ /*
+ * Maintain sane values if we got a temporary overflow.
+ */
+ if (unlikely(t->io_period > t->total_period))
+ t->io_period = t->total_period;
+ }
+
+skip_limit:
+ spin_unlock_irqrestore(&throttle_spinlock, flags);
+}
+
+
static void wake(struct dm_kcopyd_client *kc)
{
queue_work(kc->kcopyd_wq, &kc->kcopyd_work);
@@ -348,6 +462,8 @@ static void complete_io(unsigned long error, void *context)
struct kcopyd_job *job = (struct kcopyd_job *) context;
struct dm_kcopyd_client *kc = job->kc;
+ io_job_finish(kc->throttle);
+
if (error) {
if (job->rw & WRITE)
job->write_err |= error;
@@ -389,6 +505,8 @@ static int run_io_job(struct kcopyd_job *job)
.client = job->kc->io_client,
};
+ io_job_start(job->kc->throttle);
+
if (job->rw == READ)
r = dm_io(&io_req, 1, &job->source, NULL);
else
@@ -695,7 +813,7 @@ int kcopyd_cancel(struct kcopyd_job *job, int block)
/*-----------------------------------------------------------------
* Client setup
*---------------------------------------------------------------*/
-struct dm_kcopyd_client *dm_kcopyd_client_create(void)
+struct dm_kcopyd_client *dm_kcopyd_client_create(struct dm_kcopyd_throttle *throttle)
{
int r = -ENOMEM;
struct dm_kcopyd_client *kc;
@@ -708,6 +826,7 @@ struct dm_kcopyd_client *dm_kcopyd_client_create(void)
INIT_LIST_HEAD(&kc->complete_jobs);
INIT_LIST_HEAD(&kc->io_jobs);
INIT_LIST_HEAD(&kc->pages_jobs);
+ kc->throttle = throttle;
kc->job_pool = mempool_create_slab_pool(MIN_JOBS, _job_cache);
if (!kc->job_pool)
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index e2ea977..d053098 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -82,6 +82,9 @@ struct mirror_set {
struct mirror mirror[0];
};
+DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(raid1_resync_throttle,
+ "A percentage of time allocated for raid resynchronization");
+
static void wakeup_mirrord(void *context)
{
struct mirror_set *ms = context;
@@ -1111,7 +1114,7 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
goto err_destroy_wq;
}
- ms->kcopyd_client = dm_kcopyd_client_create();
+ ms->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle);
if (IS_ERR(ms->kcopyd_client)) {
r = PTR_ERR(ms->kcopyd_client);
goto err_destroy_wq;
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 58c2b58..c0e0702 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -124,6 +124,9 @@ struct dm_snapshot {
#define RUNNING_MERGE 0
#define SHUTDOWN_MERGE 1
+DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle,
+ "A percentage of time allocated for copy on write");
+
struct dm_dev *dm_snap_origin(struct dm_snapshot *s)
{
return s->origin;
@@ -1108,7 +1111,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
goto bad_hash_tables;
}
- s->kcopyd_client = dm_kcopyd_client_create();
+ s->kcopyd_client = dm_kcopyd_client_create(&dm_kcopyd_throttle);
if (IS_ERR(s->kcopyd_client)) {
r = PTR_ERR(s->kcopyd_client);
ti->error = "Could not create kcopyd client";
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 303e11d..35d9d03 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -26,6 +26,9 @@
#define PRISON_CELLS 1024
#define COMMIT_PERIOD HZ
+DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(snapshot_copy_throttle,
+ "A percentage of time allocated for copy on write");
+
/*
* The block size of the device holding pool data must be
* between 64KB and 1GB.
@@ -1642,7 +1645,7 @@ static struct pool *pool_create(struct mapped_device *pool_md,
goto bad_prison;
}
- pool->copier = dm_kcopyd_client_create();
+ pool->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
if (IS_ERR(pool->copier)) {
r = PTR_ERR(pool->copier);
*error = "Error creating pool's kcopyd client";
generated by cgit v0.10.2 at 2024-11-16 17:10:52 (GMT)